﻿// Attributes.java - attribute list with Namespace support
// http://www.saxproject.org
// Written by David Megginson
// NO WARRANTY!  This class is in the public domain.
// $Id$
using System;

namespace org.xml.sax
{

    /**
     * Interface for a list of XML attributes.
     *
     * <blockquote>
     * <em>This module, both source code and documentation, is in the
     * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
     * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
     * for further information.
     * </blockquote>
     *
     * <p>This interface allows access to a list of attributes in
     * three different ways:</p>
     *
     * <ol>
     * <li>by attribute index;</li>
     * <li>by Namespace-qualified name; or</li>
     * <li>by qualified (prefixed) name.</li>
     * </ol>
     *
     * <p>The list will not contain attributes that were declared
     * #IMPLIED but not specified in the start tag.  It will also not
     * contain attributes used as Namespace declarations (xmlns*) unless
     * the <code>http://xml.org/sax/features/namespace-prefixes</code> 
     * feature is set to <var>true</var> (it is <var>false</var> by 
     * default).
     * Because SAX2 conforms to the original "Namespaces in XML"
     * recommendation, it normally does not
     * give namespace declaration attributes a namespace URI.
     * </p>
     *
     * <p>Some SAX2 parsers may support using an optional feature flag
     * (<code>http://xml.org/sax/features/xmlns-uris</code>) to request
     * that those attributes be given URIs, conforming to a later
     * backwards-incompatible revision of that recommendation.  (The
     * attribute's "local name" will be the prefix, or "xmlns" when
     * defining a default element namespace.)  For portability, handler
     * code should always resolve that conflict, rather than requiring
     * parsers that can change the setting of that feature flag.  </p>
     *
     * <p>If the namespace-prefixes feature (see above) is
     * <var>false</var>, access by qualified name may not be available; if
     * the <code>http://xml.org/sax/features/namespaces</code> feature is
     * <var>false</var>, access by Namespace-qualified names may not be
     * available.</p>
     *
     * <p>This interface replaces the now-deprecated SAX1 {@link
     * org.xml.sax.AttributeList AttributeList} interface, which does not 
     * contain Namespace support.  In addition to Namespace support, it 
     * adds the <var>getIndex</var> methods (below).</p>
     *
     * <p>The order of attributes in the list is unspecified, and will
     * vary from implementation to implementation.</p>
     *
     * @since SAX 2.0
     * @author David Megginson
     * @version 2.0.1 (sax2r2)
     * @see org.xml.sax.helpers.AttributesImpl
     * @see org.xml.sax.ext.DeclHandler#attributeDecl
     */
    public interface Attributes
    {


        ////////////////////////////////////////////////////////////////////
        // Indexed access.
        ////////////////////////////////////////////////////////////////////


        /**
         * Return the number of attributes in the list.
         *
         * <p>Once you know the number of attributes, you can iterate
         * through the list.</p>
         *
         * @return The number of attributes in the list.
         * @see #getURI(int)
         * @see #getLocalName(int)
         * @see #getQName(int)
         * @see #getType(int)
         * @see #getValue(int)
         */
        int getLength();


        /**
         * Look up an attribute's Namespace URI by index.
         *
         * @param index The attribute index (zero-based).
         * @return The Namespace URI, or the empty string if none
         *         is available, or null if the index is out of
         *         range.
         * @see #getLength
         */
        String getURI(int index);


        /**
         * Look up an attribute's local name by index.
         *
         * @param index The attribute index (zero-based).
         * @return The local name, or the empty string if Namespace
         *         processing is not being performed, or null
         *         if the index is out of range.
         * @see #getLength
         */
        String getLocalName(int index);


        /**
         * Look up an attribute's XML qualified (prefixed) name by index.
         *
         * @param index The attribute index (zero-based).
         * @return The XML qualified name, or the empty string
         *         if none is available, or null if the index
         *         is out of range.
         * @see #getLength
         */
        String getQName(int index);


        /**
         * Look up an attribute's type by index.
         *
         * <p>The attribute type is one of the strings "CDATA", "ID",
         * "IDREF", "IDREFS", "NMTOKEN", "NMTOKENS", "ENTITY", "ENTITIES",
         * or "NOTATION" (always in upper case).</p>
         *
         * <p>If the parser has not read a declaration for the attribute,
         * or if the parser does not report attribute types, then it must
         * return the value "CDATA" as stated in the XML 1.0 Recommendation
         * (clause 3.3.3, "Attribute-Value Normalization").</p>
         *
         * <p>For an enumerated attribute that is not a notation, the
         * parser will report the type as "NMTOKEN".</p>
         *
         * @param index The attribute index (zero-based).
         * @return The attribute's type as a string, or null if the
         *         index is out of range.
         * @see #getLength
         */
        String getType(int index);


        /**
         * Look up an attribute's value by index.
         *
         * <p>If the attribute value is a list of tokens (IDREFS,
         * ENTITIES, or NMTOKENS), the tokens will be concatenated
         * into a single string with each token separated by a
         * single space.</p>
         *
         * @param index The attribute index (zero-based).
         * @return The attribute's value as a string, or null if the
         *         index is out of range.
         * @see #getLength
         */
        String getValue(int index);



        ////////////////////////////////////////////////////////////////////
        // Name-based query.
        ////////////////////////////////////////////////////////////////////


        /**
         * Look up the index of an attribute by Namespace name.
         *
         * @param uri The Namespace URI, or the empty string if
         *        the name has no Namespace URI.
         * @param localName The attribute's local name.
         * @return The index of the attribute, or -1 if it does not
         *         appear in the list.
         */
        int getIndex(String uri, String localName);


        /**
         * Look up the index of an attribute by XML qualified (prefixed) name.
         *
         * @param qName The qualified (prefixed) name.
         * @return The index of the attribute, or -1 if it does not
         *         appear in the list.
         */
        int getIndex(String qName);


        /**
         * Look up an attribute's type by Namespace name.
         *
         * <p>See {@link #getType(int) getType(int)} for a description
         * of the possible types.</p>
         *
         * @param uri The Namespace URI, or the empty String if the
         *        name has no Namespace URI.
         * @param localName The local name of the attribute.
         * @return The attribute type as a string, or null if the
         *         attribute is not in the list or if Namespace
         *         processing is not being performed.
         */
        String getType(String uri, String localName);


        /**
         * Look up an attribute's type by XML qualified (prefixed) name.
         *
         * <p>See {@link #getType(int) getType(int)} for a description
         * of the possible types.</p>
         *
         * @param qName The XML qualified name.
         * @return The attribute type as a string, or null if the
         *         attribute is not in the list or if qualified names
         *         are not available.
         */
        String getType(String qName);


        /**
         * Look up an attribute's value by Namespace name.
         *
         * <p>See {@link #getValue(int) getValue(int)} for a description
         * of the possible values.</p>
         *
         * @param uri The Namespace URI, or the empty String if the
         *        name has no Namespace URI.
         * @param localName The local name of the attribute.
         * @return The attribute value as a string, or null if the
         *         attribute is not in the list.
         */
        String getValue(String uri, String localName);


        /**
         * Look up an attribute's value by XML qualified (prefixed) name.
         *
         * <p>See {@link #getValue(int) getValue(int)} for a description
         * of the possible values.</p>
         *
         * @param qName The XML qualified name.
         * @return The attribute value as a string, or null if the
         *         attribute is not in the list or if qualified names
         *         are not available.
         */
        String getValue(String qName);

    }

    // end of Attributes.java
}